A senior Tory MP today called for an investigation into whether MI5 mistakenly recruited al-Qaida sympathisers.

Patrick Mercer, the chairman of the counter-terrorism subcommittee, said six Muslim recruits had been thrown out of the service because of serious concerns over their pasts.

The MP said he was writing to the home secretary, Alan Johnson, to call for an investigation into the matter.

Two of the six men allegedly attended al-Qaida training camps in Pakistan while the others had unexplained gaps of up to three months in their CVs.

Mercer told the Telegraph that the September 11 2001 terror attacks on the US should have prompted the British government to expand the security services, but this did not happen until the bombings on London’s transport network on 7 July 2005.